#include <stdio.h>
#include <string.h>

void *MyStrcat(char *s1, const char *s2)
{
    while(*s1 != '\0')
    {
        s1++;
    } 
    while(*s2 != '\0')
    {
        *s1++ = *s2++;
    }
    *s1 = '\0';
}

int main()
{
    char p1[] = "hello";
    char p2[] = "world";
    MyStrcat(p1,p2);
    printf("%s\n",p1);

    return 0;
}